<template>
  <a-tree :load-data="onLoadData" :tree-data="treeData" />
</template>

<script>
  export default {
    data() {
      return {
        treeData: [
          { title: 'Expand to load', key: '0' },
          { title: 'Expand to load', key: '1' },
          { title: 'Tree Node', key: '2', isLeaf: true },
        ],
      };
    },
    methods: {
      onLoadData(treeNode) {
        // return new Promise(resolve => {
        //   if (treeNode.dataRef.children) {
        //     // resolve();
        //     return;
        //   }
        // setTimeout(() => {
        treeNode.dataRef.children = [
          { title: 'Child Node', key: `${treeNode.eventKey}-0` },
          { title: 'Child Node', key: `${treeNode.eventKey}-1` },
        ];
        this.treeData = [...this.treeData];
        // resolve();
        // }, 1000);
        // });
      },
    },
  };
</script>